Since 1886 when the first oil was discovered and subsequently produced in the Middle East on Gemsa Peninsula, the Gulf of Suez has challenged the imaginations of geologists and continues to do so. The Gulf of Suez stretches over 300 km between the city of Suez and Ras Mohamed (Figures 1–3). The modern sea inundates only one-third of the geologic graben feature between the Sinai basement uplift and the Eastern Desert mountains. For simplicity, the whole graben system onshore and offshore is referred to as Gulf of Suez or "Clysmic Gulf" ("Clysma" being the Roman name of Suez) (Hume, 1921; Heybroek, 1965).
The water body of the Gulf of Suez is rather shallow with a water depth of meters. Only in the southern part off Ras Mohamed does a deeper trench enter the gulf from the Red Sea. We define the southern end of the gulf as the line from Ras Mohamed to Shadwan Island and Hurghada. This line follows approximately a 200-m water-depth contour, where the Red Sea begins. The Gulf of Suez is the northern extension of the 2000-km-long Red Sea rift system, which is a Cenozoic structure slicing through the once-continuous Arabo-African craton. Geologically, the Gulf of Suez is a complex graben/half-graben system located between two basement uplifts—the Sinai and the Eastern Desert mountains. The graben cuts through older structural trends having ages from Precambrian to Eocene. The structure of the Gulf of Suez is dominated by normal faults and tilted fault blocks, which were formed after the Oligocene, mainly during Miocene time. The axial portion of the gulf underwent the most subsidence and contains the thickest deposits of lower Miocene sediments and middle/upper Miocene evaporites. In contrast to the Red Sea graben system, where motion is presently occurring along its entire length, the Gulf of Suez experienced extension primarily during Miocene time.
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Interior Rift Basins
Not only are rift basins the foundation for much of the geologic history of the earth, but they also are very attractive areas for hydrocarbon accumulations. Klemme stated that this geographic area has provided significant hydrocarbon reserves: "By area, these basins represent slightly over 5% of the world's basins (50% productive). However, high recovery has resulted, as they contain 10% of the world's present reserves (12% of the oil reserves and 4% of the gas reserves)." The rift basins discussed in this volume are only a few of the productive and, more importantly, potentially productive rift basins in the world. The term "rift" was coined by Gregory (1896) for the graben that now bears his name in the Kenyan portion of the East African rift system. The study of geology of rift basins began in the Rhine graben. The discovery of hydrocarbons in rift basins about the turn of the century provided new motivation for understanding these basins. This publication was initiated by the AAPG Publications Committee in 1985 and contributors were invited to write. AAPG designed their "World Petroleum Basins" series and sought to publish the definitive volume on each of several basin types. In this volume, "Interior Rift Basins," a detailed, 3-paper overview was written about the Suez Rift basin as representative of interior rift basins. The key papers were followed by less detailed reviews of three other selected interior basins: Pripyat and Dnieper-Donets Basins; Reconcavo Basin, Brazil; Albuquerque Basin Segment of the Rio Grande Rift.